Integration Patterns for Legacy Systems

The Legacy System Challenge

Most organisations run critical business processes on legacy systems that were never designed to integrate with modern cloud platforms. Connecting these systems to Power Platform requires careful planning and the right integration patterns.

Pattern 1: Direct Database Connectivity

Power Platform can connect directly to on-premises databases using the Data Gateway. This works well for read-heavy scenarios like reporting and analytics. Consider using views to abstract complexity and improve security by limiting direct table access.

Pattern 2: API-Based Integration

If your legacy system has APIs (REST, SOAP, or custom), use Power Automate custom connectors to create reusable integration points. This approach provides better abstraction and can include business logic and validation.

Pattern 3: File-Based Integration

For systems without APIs or direct database access, file-based integration remains viable. Set up automated processes to export data to SharePoint or OneDrive, then use Power Automate to process files and load data into your target systems.

Pattern 4: Message Queue Integration

For high-volume or real-time integration needs, consider message queues like Azure Service Bus. Legacy systems can publish messages to queues, which Power Automate monitors and processes asynchronously.

Handling Authentication and Security

Legacy systems often use outdated authentication methods. Store credentials securely using Azure Key Vault. Consider implementing an integration layer (Azure Functions or Logic Apps) that handles authentication complexity.

Error Handling and Monitoring

Build robust error handling into your integration flows. Log all integration activities, implement retry logic for transient failures, and set up alerts for critical errors. Use Power Automate's built-in monitoring for comprehensive observability.